How Much Insulation for a 24x24 Garage?
Bags or rolls
7 bags
The four walls of a 24 by 24 garage at 8 foot plate height, 96 linear feet of wall, framed at 16 inches on center.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Wall or ceiling area768 sq ft
- Stud or joist spacing16 in
- Coverage per bag or roll106.8 sq ft
Bags or rolls7 bags
| Gross area | 768 sq ft |
|---|---|
| Framing factor at 16 in oc | 90% |
| Cavity area to insulate | 691 sq ft |
| Bags at 106.8 sq ft | 7 |
| Coverage bought | 748 sq ft |
The material list this produces
| Insulation batts, bags | 7 |
|---|---|
| Vapor retarder, sq ft (if required) | 768 |
Coverage per bag compared
Bag coverage is the number that decides this, and it is printed on the bag. Here is the same area at five coverages, from 40 square feet a bag up to the 106.8 default.
| Coverage per bag | Bags or rolls | Coverage bought |
|---|---|---|
| 40 sq ft | 18 bags | 720 sq ft |
| 50 sq ft | 14 bags | 700 sq ft |
| 75 sq ft | 10 bags | 750 sq ft |
| 90 sq ft | 8 bags | 720 sq ft |
| 106.8 sq ft | 7 bags | 748 sq ft |
What else matters here
A 24 by 24 garage has 96 linear feet of wall, which at an 8 foot plate height is 768 square feet gross. Take the framing out and there are 691 square feet of cavity, so seven bags does the walls.
If the door wall is being insulated as framed wall above and beside the opening, deduct the opening: a 16 by 7 foot door takes 112 square feet off and the count drops to six bags.
The ceiling is a separate order.
What this calculator assumes
- Framing takes up roughly 10 percent of a wall at 16 inch on center and 7 percent at 24. Cavity area is reduced accordingly, so you do not buy insulation for the studs.
- Bag coverage varies a lot by R value and width. The default is a common R-13 kraft faced batt bag; read your own bag and change it.
Questions people ask
How many bags of insulation for a 24x24 garage?
Seven bags for the walls, based on 768 square feet of gross wall area and 691 square feet of cavity. The ceiling is extra.
Do I deduct the garage door?
Yes, if you are insulating only the framed wall. A 16 by 7 foot door is 112 square feet of wall you are not filling, and taking it off drops the count from seven bags to six.
How much does one bag of batts cover?
It is printed on the bag and it moves with R value and width. The default here is a common R-13 kraft faced batt bag at 106.8 square feet. Change it to whatever you are actually buying before you trust the count.
The insulation calculator takes any dimensions you like and hands back the same list.
Other common sizes
23 more sizes are answered on the insulation calculator page